You asked a question which no one can answer because it is what matters to YOU that counts. It's not the sort of questions like lens/body A is better than lens/body B in which a definite answer can be given.

On the one hand the 70-200/2.8 IS will be a lot better as a low light tool but for wildlife, the added reach of 100-400 is beneficial.

One final parameter you should consider is weight. Both lenses are heavy, a lot heavier than your current lens. As a guy who takes its camera everywhere, you may be better with the 70-300 DO. Optical quality will not be on par with the above but heavy lenses often suffer from a tendency to be left at home :-(

No lens characteristic is useful by itself. A lens that is long enough for the job but which has an unusably small aperture (shots are unacceptably motion blurred even at maximum practical ISO) is still useless. An f/1.4 prime that is too short for the job is similarly useless. You need to look at the big picture, not just one characteristic.

What lens is "best" for you depends heavily on what YOU shoot, and the lighting conditions under which you're shooting. For example, yesterday I shot an all-day Christian music festival. I used 2 bodies; the 1Ds, and the 1D-MkII. During the day, I hat the 35-350/3.5-5.6L on the 1D-MkII,and the 17-40/4L on the 1Ds, and was shooting AV mode at f/8 and getting acceptably fast shutter speeds. But in the late afternoon, I replaced them with the 70-200/2.8L on the 1D-MkII and the 24-70/2.8L on the 1Ds and bumped up the ISO quite a bit. As the shooting conditions changed, the lenses that were "right" for the job changed as well.

While the 70-200/2.8L IS is an excellent lens, it is not appropriate or optimal in many situations. No lens is. Only you can tell what's best for you, because only you know exactly what you shoot and the lighting conditions un which you're shooting it. For the forum members here to advise you intelligently would require us to be psychic.

Something I'm surprised hasn't been mentioned is the option of running the 70-200 f2.8 with a 2x converter. That way you get the fast benifits of the 2.8 lens but when focal length becomes more important you can have a 140-400 f5.6.

The lens with a converter on is probably not going to quite match the optical quality of the 100-400 but you do get 2 lenses for the price of one and a 5th

I'm new to these fourms, though not to the website. I'm sure that this kind of question is quite often overasked, but I could use your opinions.

First, background. I am not professional by any means, I am a still fairly new photographer who got started by shooting highschool sports events for a highschool student newspaper. I hope to contenue to do so for college in the next 4 years. Please do not look down on me because of this. While I know that by saying I am a student who worked for a student newspaper I open myself up for certain criticism, everyone has to start somewhere. (Rant finished)

Anyway, I shoot a little of everything. I love shooting wildlife(as much as the small game I live by can be called that), I shoot landscapes, I would like to keep shooting sports in college for the college publication, those around me are a constant source of photo-fodder, basically I am one of those "i take my camera everywhere" sort of guys.

After a considerable amount of time saving/working I am ready to buy a new lens. This is quite nice because I have been on a tight budget. I have a Canon 300D Rebel w/kit lens and a 70-300 f/4-5.6 zoom. Originally, I had my heart dead set on the Canon 70-200 f/2.8 IS lens. I still think this would be an excellent investment for me. I am often lacking in low light capability, and the f/2.8 would be very helpful. However I recently got to play with the Canon 100-400 f/4-5.6 IS. I now wonder if this would be a better buy if for no other reason than the focal length, which would be a boon for wildlife.

Basically, it comes down to this: should I value length or aperature? And, which lens would be the most usefull in the future (sports/wildlife/landscape)

Yes, this is a rather mundane and materialistic question, but I would like to hear the advice of this fourm. Thanks!

I'm new to these fourms, though not to the website. I'm sure that this kind of question is quite often overasked, but I could use your opinions.

First, background. I am not professional by any means, I am a still fairly new photographer who got started by shooting highschool sports events for a highschool student newspaper. I hope to contenue to do so for college in the next 4 years. Please do not look down on me because of this. While I know that by saying I am a student who worked for a student newspaper I open myself up for certain criticism, everyone has to start somewhere. (Rant finished)

Anyway, I shoot a little of everything. I love shooting wildlife(as much as the small game I live by can be called that), I shoot landscapes, I would like to keep shooting sports in college for the college publication, those around me are a constant source of photo-fodder, basically I am one of those "i take my camera everywhere" sort of guys.

After a considerable amount of time saving/working I am ready to buy a new lens. This is quite nice because I have been on a tight budget. I have a Canon 300D Rebel w/kit lens and a 70-300 f/4-5.6 zoom. Originally, I had my heart dead set on the Canon 70-200 f/2.8 IS lens. I still think this would be an excellent investment for me. I am often lacking in low light capability, and the f/2.8 would be very helpful. However I recently got to play with the Canon 100-400 f/4-5.6 IS. I now wonder if this would be a better buy if for no other reason than the focal length, which would be a boon for wildlife.

Basically, it comes down to this: should I value length or aperature? And, which lens would be the most usefull in the future (sports/wildlife/landscape)

Yes, this is a rather mundane and materialistic question, but I would like to hear the advice of this fourm. Thanks!

Welcome!

My suggestion would be to use what you have, and work out from experience what you miss the most. If you're always at the 300mm end of the 75-300mm zoom, then perhaps you want a longer lens next. Or if you are always using higher ISO settings to get faster shutter speeds, then perhaps faster lenses are what you want. Or if you are always at 18mm with the kit lens wishing it was wider, add something like the 10-22mm zoom to your shopping list.

You might like to pick up one fast prime to get some experience with a fast lens. The 50mm f/1.8 is very inexpensive, although effectively an 80mm lens on a 300D, which you may or may not find terribly useful.

I'd also recommend that you read Bob Atikins' discussion of lenses for the 300D, 20D et al:

I have a similar set up to yours and struggled with the same dilemna. I like to sit back at events and snipe candid shots of people. In order to do so I need both the a telephoto range and light sensitivity. After all a flash is a dead give away. I ultimately opted to go with a 70 to 300 DO lens for several reasons. 1. The Quality that it produces 2. the image stabilization allows you to get shots you could not get without it and especially the size. For a lens of that magnification it is very small and inconspicuous. Try carrying a massive 70 to 200 2.8 into a party or on the street and see how well you blend in. Would I like even more magnification? Rarely. Remember that with a 1.6 multiplication factor on the Rebel body we are talking about a 112 to 480 lens.

As several people have said the choice of lenses is a very personal thing. Take time and get to know the type of pictures you shoot. I just want to add two other factors in your thinking. for me the size of the lens and image stabilization are just as important factors as the length and apature. My 70 to 300 DO goes everywhere I go. A massive 70 to 200 wouldn't.

PS. Have you tried your rebel at a higher ISO? If you haven't then try it. I shoot a lot of indoor shots without a flash at 1600 ISO. They are absolutely clean and the quality remains impressive.